User-generated content is becoming pervasive on the World Wide Web due to the increasing popularity of social networks, blogs, review websites, etc. Such content is often in the form of comments (e.g., a comment by a first user pertaining to content shared by a second user within a social network, a user comment in response to an article in a columnist's blog, a user comment pertaining to a video clip posted on a content hosting website, etc.), user reviews (e.g., of products, movies, etc.), user actions (e.g., Like!, Dislike!, +1, sharing, bookmarking, playlisting, etc.), and so forth.